"All of them require physical access to these machines, and I don't let strangers play with my machines," Shelby County Election Commission Administrator Linda Phillips said. "Even people repairing the air conditioning are watched by our staff."

Tennessee Secretary of State Tre Hargett said he doesn't believe the system is vulnerable, but they must be vigilant and prepared.

“They’re not hooked to the Internet,” Phillips said. “You can’t hack into them.”

If only it was that simple. Researchers say voting machines can be hacked if it’s done in person. In 2006, a group of Princeton researchers claimed they hacked into a voting machine in less than a minute.

They were able to install malicious software they said could change votes and the outcome of elections. The machine they hacked into was a Diebold AccuVote-TS.

Shelby County uses Diebold AccuVote-TSX.

Despite the similarities, Philips said hacks like that won't happen here. "All of them require physical access to these machines and I don't let strangers play with my machines,” Phillips said. Phillips said poll workers would notice someone messing with the machines on or before election day.

Each machine has security seals to indicate when it's been tampered with.

"It clearly says void, and if someone had tried to put it back we’d know it had been tampered with because see how it looks very different?” Phillips said.

Phillips gave WMC5 a look inside the election commission’s operations center and warehouse, where the county’s 1,505 voting machines are stored throughout the year.

She said the machines are monitored around the clock by cameras, and not just anyone can walk in. All guests must be accompanied.

"Even people repairing the air conditioning are watched by our staff,” Phillips said.

However, that’s not good enough for the Shelby County Advocates for Valid Elections.

The group, led by former Memphis City Councilor Carol Chumney, released a report last year, detailing a wide-range of problems that go beyond electronic hacking.

This month, the group sued Phillips and Tennessee Secretary of State and Hargett, claiming the county's elections are "vulnerable to undetectable manipulation.”

That’s partly because the machines, which are more than a decade old, don't produce a voter-verifiable paper trail.

Hargett did not respond to our requests for an interview, but in February, he responded to receiving an "F" grade for election security from the Center for American Progress.

“Look at the source,” Hargett said in February.

He dismissed even the suggestion that our voting system is at risk.

“The biggest threat to Tennessee elections, quite frankly though, is the disinformation,” Hargett said. “I don’t believe our system is vulnerable, but I will say this, we have to be vigilant and we prepare and we worry so Tennessee citizens don’t have to, that’s our job."

In February, Tennessee lawmakers rejected a bill that would’ve required a paper receipt for all ballots cast in the state, citing the millions of dollars it would’ve cost to pull that off.

In Shelby County, commissioners will decide how much to spend on new voting machines after the midterms.

“The new equipment that we hope to have some time next year will have some sort of voter verifiable paper trail,” Phillips said.

This year, the best way to ensure election security in Shelby County is to show up and vote.

"What we want is for people to participate in the elections and know they have confidence in how their votes are counted,” Hargett said.